Devices Employing Colloidal-Sized Particles

Abstract

The present invention relates to the use colloidal particles to realize photonic and microfluidic devices. In particular embodiments, colloidal particles are used to realize microfluidic a two-way valve, three-way valve, check valve, three-dimensional valve, peristalsis pump, rotary pump, vane pump, and two-lobe gear pump. In certain embodiments, actuation of an active element in the microfluidic structure is accomplished by electrophoresis, the use of an optical trap or “tweezer”, or the application of an electric field or magnetic field. In other embodiments, the application of an electrical field to colloidal particles that are substantially constrained to two dimensional movement is used to realize wave guides, filters and switches for optical signals.

1 . A microfluidic structure comprising: 
 a structure defining an input structure for receiving a microfluidic stream, an output structure for transmitting a microfluidic stream, and a space between said input structure and said output structure;    a colloidal structure located in said space between said input structure and said output structure; and    means for applying a field to said colloidal structure to manipulate a microfluidic stream between said input structure and said output structure.    
     
     
         2 . A microfluidic structure, as claimed in  claim 1 , wherein: 
 said input structure lies in a first plane;    said output structure lies in a second plane that is substantially parallel to and separated from said first plane;    said space comprises a communication path extending between said input structure and said output structure;    said colloidal structure comprises a colloidal particle.    
     
     
         3 . A microfluidic structure, as claimed in  claim 2 , wherein: 
 said means for applying a field comprises means for applying one of the following: an electric field, a magnetic field, and an optical trap.    
     
     
         4 . A microfluidic structure, as claimed in  claim 1 , wherein: 
 said colloidal structure comprises a string of colloidal particles having a first end that is operatively attached to said structure and a second free end that is capable of rotating about said first end.    
     
     
         5 . A microfluidic structure, as claimed in  claim 1 , wherein: 
 said space comprises a closed loop with a first portion of said closed loop extending along a portion of a straight line extending between said input structure and said output structure and a second portion that does not extend along a straight line between said input structure and said output structure.    
     
     
         6 . A microfluidic structure, as claimed in  claim 5 , wherein: 
 said closed loop has a width that is greater than a width of said output structure.    
     
     
         7 . A microfluidic structure, as claimed in  claim 5 , wherein: 
 said colloidal structure comprises multiple colloidal particles, each located in said closed loop.    
     
     
         8 . A microfluidic structure, as claimed in  claim 5 , wherein: 
 said colloidal structure comprises four colloidal particles, each located in said closed loop.    
     
     
         9 . A microfluidic structure, as claimed in  claim 5 , wherein: 
 said means for applying a field comprises means for applying one of the following: an electric field, a magnetic field, and an optical trap.    
     
     
         10 . A microfluidic structure, as claimed in  claim 1 , wherein: 
 said colloidal structure comprises a string of colloidal particles.    
     
     
         11 . A microfluidic structure, as claimed in  claim 10 , wherein: 
 said means for applying a field includes means for applying one of the following: an electric field, a magnetic field, and an optical trap.    
     
     
         12 . A microfluidic structure, as claimed in  claim 1 , further comprising: 
 a rotatable vane structure having a hub, a first arm extending from said hub, and a second arm extending from said hub, said rotatable vane structure located within said space.    
     
     
         13 . A microfluidic structure, as claimed in  claim 12 , wherein: 
 said colloidal structure comprises a colloidal particle operatively attached to one of said first and second arms of said rotatable vane.    
     
     
         14 . A microfluidic structure, as claimed in  claim 12 , wherein: 
 said means for applying a field comprises pairs of electrodes for producing an electrical field that causes said colloidal particle to move by electrophoresis.    
     
     
         15 . A microfluidic structure, as claimed in  claim 12 , wherein: 
 said colloidal structure comprises a plurality of colloidal particles fixedly located in said structure adjacent to said rotatable vane.    
     
     
         16 . A microfluidic structure, as claimed in  claim 12 , wherein: 
 said means for applying a field comprises means for applying one of the following: an electric field, a magnetic field, and an optical trap.    
     
     
         17 . A microfluidic structure, as claimed in  claim 1 , wherein: 
 said colloidal structure comprises a first pair of colloidal particles for forming a first lobe and a second pair of colloidal particles for forming a second lobe.    
     
     
         18 . A microfluidic structure, as claimed in  claim 1 , wherein: 
 said means for applying a field comprises an optical trap mechanism for use in causing said first lobe to rotate in a clockwise direction and said second lobe to rotate in a counter-clockwise direction.    
     
     
         19 . A photonic structure comprising: 
 a structure for confining a plurality of colloidal particles that comprises a first plate and a second plate that is substantially parallel to said first plate and separated from said first plate by a distance that substantially constrains colloidal particles located between said first and second plates to two-dimensional motion;    a plurality of colloidal particles located between said first and second plates;    means for applying a first electrical field to said plurality of colloidal particles, said first electrical field comprising a component that is normal to said first and second plates; and    means for facilitating the entry of light into a space located between said first and second plates.    
     
     
         20 . A photonic structure, as claimed in  claim 19 , further comprising: 
 means for preventing said plurality of colloidal particles from occupying a predetermined space between said first and second plates that defines a propagation path for a light signal that is propagating in a direction that is substantially parallel to said first and second plates.    
     
     
         21 . A photonic structure, as claimed in  claim 20 , wherein: 
 said means for preventing comprises a wall that is located between said first and second plates and defines said predetermined space by preventing any of said plurality of colloidal particles from existing in a space between said first and second plates that is at least partially occupied by said wall.    
     
     
         22 . A photonic structure, as claimed in  claim 21 , wherein: 
 said wall extends from said first plate towards said second plate.    
     
     
         23 . A photonic structure, as claimed in  claim 20 , wherein: 
 said means for preventing includes means for producing an optical trap that defines said predetermined space.    
     
     
         24 . A photonic structure, as claimed in  claim 20 , wherein: 
 said means for preventing comprises means for applying a second electrical field that extends between said first and second plates and has a greater magnitude than said first electrical field.    
     
     
         25 . A photonic structure, as claimed in  claim 19 , wherein: 
 said means for directing comprises means for directing light in a direction that has a component that is normal to a plane occupied by one of said first and second plates.    
     
     
         26 . A photonic structure, as claimed in  claim 25 , wherein: 
 said first plate comprises first polarizing filter and said second plate comprises a second polarizing filter that is substantially perpendicular to said first polarizing filter.    
     
     
         27 . A photonic structure comprising: 
 a structure for confining a plurality of colloidal particles that comprises a first plate, a second plate that is substantially parallel to said first plate and separated from said first plate by a distance that substantially constrains colloidal particles located between said first and second plates to two-dimensional motion, and a third plate that is substantially parallel to said second plate and separated from said second plate by a distance that substantially constrains colloidal particles located between said second and third plates to two dimensional motion;    a first plurality of colloidal particles located between said first and second plates of said structure;    a second plurality of colloidal particles located between said second and third plates of said structure;    first means for applying a first electrical field that extends between said first and second plates;    second means for applying a second electrical field that extends between said second and third plates;    means for facilitating the engagement of light with said structure so that the light has a component that is normal to a plane occupied by one of said first, second and third plates.    
     
     
         28 . A photonic structure, as claimed in  claim 27 , wherein: 
 said first plate comprises a first polarizing filter, said second plate comprises a second polarizing filter that is substantially perpendicular to said first polarizing filter, and said third plates comprises a third polarizing filter that is substantially perpendicular to said second polarizing filter.